Ream wrap is the wrapper around the packages of cut size (8½×11 etc.) paper that is used for printers, copy machines, etc. This wrapper has traditionally been paper (poly coated or two papers laminated with poly), plastic film, or a paper/solid plastic film combination.
U.S. Pat. No. 5,250,348 relates to an improved wrapper paper for use in very low contact pressure applications. A wrapper paper for pressure sensitive products bearing on one of its flat surfaces a layer of polyethylene and on the opposite of its flat surfaces a layer of a primer selected from the polyalkyleneimine class, at least portions of the opposite flat coated surfaces facing one another in overlapping relationship when the paper is wrapped about a product, the overlying areas of the wrapper paper being sealed to one another by heat means and the application of very low pressure to the overlapping portions. The invention relates to wrapper papers for pressure sensitive products, such as paper employed in the wrapping for storage and shipping of ream quantities of carbonless printing papers.
U.S. Pat. No. 5,989,724 relates to a recyclable and repulpable ream wrap and related methods of manufacture. Recyclable and repulpable coated paper stock, preferably for use as ream wrap, comprising a substrate coated on at least one surface with a base coat and at least one additional coat over a base coat. Both coats are water based dispersions of a polymer selected from the group consisting of acrylic polymers, acrylic copolymers, polyvinyl acetate, polyvinyl alcohol, ethylene-vinyl acetate, polyvinyl chloride, styrene butadiene copolymers, polyvinylidiene chloride and its copolymers, or starch. The wax free coating forms a pin-hole free continuous film on the substrate which is resident to water and water vapor. The invention also includes processes for making and recycling the coated stocks. The invention concerns coated paper stocks, preferably for use as ream wraps, comprised of a substrate coated on at least one surface with a base coat and at least one additional coat over said base coat both of which are applied as wax free water based polymeric dispersions.
U.S. Pat. No. 4,020,215 relates to an extrusion of polyolefin onto paper at decreased temperatures. By coating a paper substrate first with a polyalkyleneimine and then with a polymer containing groups which react chemically with the imino groups of the polyalkyleneimine, a polyolefin can be extruded onto the substrate with good adhesion at temperatures lower than the temperature that would be required to obtain the same degree of adhesion if the polymer containing the reactive groups were not present.
U.S. Pat. No. 3,230,135 relates to a process for coating paper using a polyimine precoat and products thereof. The invention relates to a method of coating paper materials with a thin polymer film, and to the polymer coated product. The invention relates to depositing of an organic polyimine which has the basic chain structure of a polyethyleneimine, interposed between a substrate and a heat-sealed polymer coating thereon, particularly a polyethylene coating, which improves adhesion and heat seal strength.
As small offices and home offices have proliferated the distribution of reams of paper has changed from boxes to large users, to retail stores and mail order for the small office/home office segments. This has placed increasing demands on the wrapper because of the increased and rougher handling of the individual reams. The result has been more reams breaking open which breaks the moisture barrier, allowing the sheets of wrapped paper to absorb moisture, get minor curl, and jam in the printer or copy machine. As a result the market needs a stronger ream wrapper. Machine direction and cross direction tear strength properties are a measure of the overall strength of the wrapper and its ability to resist breaking open.
One such ream wrap product is a poly one-side ream wrap. The poly one-side ream wrap is a sheet of paper with a low density polyethylene coating on one side. A typical paper used in this application is produced by Canfor in a 50 pound (per 3,000 sq feet) basis weight. Persons making ream wrap would put low-density polyethylene resin on the product in various weights (7 to 14 pounds of polyethylene per 3,000 sq. feet of product is a typical poly coating amount). The low-density polyethylene used is a resin produced with ethylene. Below is representative strength data for 10 pounds of low density monomer coated on paper. As shown below, this coating has increased the tear strength of the product only slightly versus plain paper utilizing paper industry strength tests (Standard TAPPI tests).
Machine DirectionCross DirectionTearTear50# Canfor Paper12213750# Canfor Paper with12414110# Polyethylene monomerStrength Gain24MD Tear test-TAPPI T-414-units grams of forceCD Tear test-TAPPI T-414-units grams of force